The invention is directed towards novel carbon monoxide containing compositions effective as plasticizers for polyvinyl chloride resins.
Polyvinyl chloride (PVC) is a versatile polymer which is used in many applications such as water piping, floor tile, exterior vinyl siding, electrical wire insulation, shower curtains and synthetic leather. Plasticizers are added to PVC to improve flow, and therefore processability, as well as to reduce the brittleness of the product. A plasticizer is a material incorporated in a plastic to increase its workability and its flexibility or distensibility (i.e., elongation). This is achieved by lowering the glass transition temperature (xe2x80x9cTgxe2x80x9d), thereby producing a change in properties from those of a hard, brittle, glasslike solid to those of a soft, flexible, tough material. The vast majority of plasticizers used today are monomeric ester-types. Phthalates such as diisononyl phthalate, diisodecyl phthalate and di(2-ethylhexyl) phthalate (dioctyl phthalate, DOP) are well known and commonly used plasticizers. Further, plasticizers are usually added to PVC on hot rolls or in a hot mixer such as a Banbury. The plasticizer content varies widely depending on the end use of the material; however, typically plasticizer content will be approximately 5 to approximately 50% by weight.
When evaluating which plasticizers should be used for a particular application, the permanence of the plasticizer, in addition to miscibility with the PVC, is crucial. Permanence refers to the stability of plasticizer within the blend. More specifically, plasticizers, especially those with low molecular weights, tend to be migratory in that they tend to move to the surface of the blend where they subsequently evaporate and/or may be removed by soapy water, solvents, oils, etc. These problems are minimized by using high molecular weight polymers. Unfortunately, very high molecular weight polymers may present processing and compatibility problems, cause poor low temperature flexibility, and be costly.
Copolymers of ethylene, carbon monoxide and a termonomer(s), such as vinyl acetate, have been used as plasticizers in blends with PVC to produce flexible films, as well as, rigid and semi-rigid materials. These plasticizers are compatible with PVC, lower the Tg and possess adequate permanence. However, while these plasticizers have proved to be effective, they are prepared using pure feeds of the individual monomers which can be costly. Hence, there is still a need to investigate other PVC plasticizers which are compatible with PVC and sufficiently lower the PVC resin""s Tg. Additionally, less expensive avenues to produce known plasticizers should also be pursued.
The instant invention provides novel polyvinyl chloride compositions having CO-containing polymers which act as plasticizers. These CO-containing polymers are low molecular weight copolymers with low crystallinity. Depending on the particular plasticizer(s) used and the type of PVC, percentage mix, etc., advantages of the instant invention include: lower plasticizer volatility and accompanying lower migration; lower cost than conventional monomeric plasticizers; improved processability and compatibility; and effective lowering of the PVC resin glass transition temperature (xe2x80x9cTgxe2x80x9d).
In one embodiment, the invention is a PVC resin composition comprising polyvinyl chloride and a plasticizer selected from the group consisting of: i) a non-linear, paraffin-soluble olefin-CO copolymer; ii) an olefin-CO-X terpolymer derived from non-pure feeds; ii) a non-linear olefin-CO copolymer derived from non-pure feeds; iv) a non-linear CO-X copolymer; and v) mixtures thereof; wherein X is selected from the group consisting of alpha-olefin, vinyl acetate, neo vinyl ester and mixtures thereof. The composition may further comprise further comprising a compound selected from the group consisting of dialkyl phthalate, dialkyl isophthalate, dialkyl terephthalate, trialkyl trimellitate, tetraalkyl pyromellitate, monoalkhyl benzoate, dialkyl azelate, dialkyl sebacate, dialkyl adipate, and mixtures thereof. The composition may also further comprising a stabilizer or filler selected from the group consisting of calcium, barium, cadmium, zinc, lead, calcium carbonate, clay, and mixtures thereof.
In another embodiment, the invention is a product prepared from the PVC resin according as described above wherein said product is selected from the group consisting of a film, a sheet, an extruded item, a molded item a cast item and mixtures thereof.
In yet another embodiment, the invention is a method for a preparing a PVC resin comprising blending polyvinyl chloride with a plasticizer selected from the group consisting of: i) a non-linear, paraffin-soluble olefin-CO copolymer; ii) an olefin-CO-X terpolymer derived from non-pure feeds; iii) a non-linear olefin-CO copolymer derived from non-pure feeds; iv) a non-linear CO-X copolymer; and v) mixtures thereof; wherein X is selected from the group consisting of alpha-olefin, vinyl acetate, neo vinyl ester and mixtures thereof. This method may further comprise the step of blending a further comprising the step of blending a compound selected from the group consisting of dialkyl phthalate, dialkyl isophthalate, dialkyl terephthalate, trialkyl trimellitate, tetra-alkyl pyromellitate, monoalkhyl benzoate, dialkyl azelate, dialkyl sebacate, dialkyl adipate, and mixtures thereof.
These and other features, aspects and advantages of the present invention will become better understood with regard to the following description and appended claims.
The instant invention relates to novel PVC/plasticizer blends and the method of producing such blends based on carbon monoxide (xe2x80x9cCOxe2x80x9d) containing plasticizers which are formed from non-pure feed streams such as synthesis gas (xe2x80x9csyngasxe2x80x9d) and multi-component synthesis gas (xe2x80x9cMCSxe2x80x9d). Pure co-feeds such as vinyl monomers, including olefins, may also be used in conjunction with non-pure feeds to form the plasticizers. These CO-containing polymers are low molecular weight (xe2x80x9cMWxe2x80x9d) copolymers with low crystallinity. It should be appreciated by those skilled in the art that use of the general term xe2x80x9ccopolymersxe2x80x9d includes terpolymers and other polymers having various combinations of different monomer units. It should also be appreciated that the term xe2x80x9cpolyvinyl chloridexe2x80x9d or xe2x80x9cPVCxe2x80x9d means homopolymers of vinyl chloride, as well as, copolymers thereof containing up to about 20% of other monomers including, but not limited to, vinyl acetate, propylene, ethylene, butyl vinyl ether, diethyl maleate, dimethyl fumarate, etc. With respect to the terms xe2x80x9cnon-purexe2x80x9d, xe2x80x9csyngasxe2x80x9d and xe2x80x9cMCSxe2x80x9d feedstreams, one skilled in the art would recognize these to be feeds other than xe2x80x9cpure feedsxe2x80x9d which are typically defined as being at or close to 100%. Non-pure feed streams are further described in U.S. Pat. No. 6,049,011 to Kiss et al. and co-pending U.S. patent application Ser. Nos. 09/233,353 and 09/233,362xe2x80x94all of which are herein incorporated by reference.
The plasticizers of this invention may be synthesized using well known free radical polymerization techniques as described in co-pending U.S. patent application Ser. Nos. 09/233,353 and 09/233,362xe2x80x94both of which are herein incorporated by reference. Because the instant invention employs free-radical polymerization to form its non-linear copolymers, the resulting non-linear copolymers may also be characterized as being non-alternating.
The instant invention provides novel polyvinyl chloride compositions having CO-containing polymers which act as plasticizers. These CO-containing polymers are low molecular weight copolymers with low crystallinity. Depending on the particular plasticizer(s) used and the type of PVC, percentage mix, etc., advantages of the instant invention include: lower plasticizer volatility; lower cost than conventional monomeric plasticizers; improved processability and compatibility; and effective lowering of the PVC resin glass transition temperature (xe2x80x9cTgxe2x80x9d).
The composition of the invention is a PVC resin which contains a novel plasticizer. More specifically, the plasticizer is selected from the following:
1) A non-linear, paraffin-soluble olefin-CO copolymer. A more detailed description of these co-polymers can be found in U.S. application Ser. No. 09/233,362 which is herein incorporated by reference.
2) An olefin-COxe2x80x94X terpolymer derived from non-pure feeds. A more detailed description of these terpolymers can be found in U.S. application Ser. No. 09/233,353 which is herein incorporated by reference. Although this terpolymer is defined as being xe2x80x9cderived from non-pure feedsxe2x80x9d, this terminology is meant to include co-feeds where at least one feed is from a non-pure source and another feed is from a pure source. For example, the non-pure feed could be from syngas or MCS while the co-feed is from a pure source such as vinyl acetate.
3) A non-linear olefin-CO copolymer derived from non-pure feeds. Here again, it should be noted that defining this copolymer as being xe2x80x9cderived from non-pure feedsxe2x80x9d, it is meant to also include co-feeds where at least one feed is from a non-pure source and another feed may be from a pure source. These copolymers may include paraffin-soluble as well as paraffin insoluble varieties. Typical molecular weights will be in the range of about 200 to 30000 and have branches in the order of 20 to 300. In a preferred embodiment, the olefin is ethylene.
4) A non-linear COxe2x80x94X copolymer where X may be an alpha-olefin, vinyl acetate, neo vinyl ester or mixtures thereof.
5) Mixtures of the plasticizers defined in 1-4.
The non-pure feeds preferably comprise a total olefin amount ranging from about 5 to about 40 mole %, carbon monoxide in an amount ranging from about 1 to about 40 mole %, hydrogen in an amount ranging from about 4 to about 55 mole %, carbon dioxide in an amount ranging from about 3 to about 10 mole %, and methane in an amount ranging from about 4 to about 85 mole %. The non-pure feeds may further comprise acetylene in an amount ranging up to about 10 mole %.
The composition may optionally contain, in addition to the plasticizers defined above, a dialkyl phthalate, or other suitable monomeric esters such as dialkyl isophthalates, dialkyl terephthalates, benzoates, trialkyl trimellitates, and the like. Preferred dialkyl phthalates are those having alkyl groups with approximately 4 to 20 carbons. In a preferred embodiment, the ratio of plasticizer to dialkyl phthalates will be in the range of 9:1 to 1:9 and the mix of these plasticizers will account for about 0.01 to 75 weight percent of the PVC resin composition. Thus, in this preferred embodiment, the polyvinyl chloride will make up approximately 25 to 99.99 weight percent of the PVC resin composition. The composition may also further comprise stabilizers, fillers, and/or other well-known additives that are commonly used in the art. Suitable stabilizers include, but are not limited to, calcium, barium, cadmium, zinc, lead and mixtures thereof. Preferably, the stabilizers will make up approximately 0.01 to 7 weight percent of the PVC resin. Suitable fillers include, but are not limited to, calcium carbonate, clay and mixture thereof. Preferably, fillers will be approximately 0.01 to 6 weight percent of the PVC resin.
The synthesis of the copolymer and terpolymer of the instant invention will advantageously occur at low pressure, free radical polymerization conditions. Such low pressure conditions are at pressures ranging from about 100 psig to about 3,000 psig, and preferably from about 500 psig to 800 psig. Additionally, the polymerization temperatures will typically range from about 50xc2x0 C. to about 300xc2x0 C., and preferably from about 50xc2x0 C. to about 200xc2x0 C.
In another embodiment, the invention is an article produced from the PVC resin composition described above. For instance, the PVC resin composition could be made into a film or a sheet. Articles can also be extruded, molded or cast from the PVC resin composition.
Also provided for is a method for a preparing a PVC resin comprising blending polyvinyl chloride with a plasticizer, as defined above. The method may further include the step of blending a dialkyl phthalate. Additionally, stabilizers and/or fillers may also be blended. Standard PVC/plasticizer blending techniques, well known to those skilled in the art, may be used such as adding the plasticizers to PVC on hot rolls or in a hot mixture such as a Banbury. Typical temperatures for such blending techniques are in the range of about 20 to 300xc2x0 C. Preferred temperature ranges are from about 50 to 230xc2x0 C. Typical pressures for these blending techniques can range widely from about 100 to 60000 psi. Preferred pressure ranges are in the range of about 100 to 30000 psi. Processing aids, such as stearic acid, may optionally be used. Thus, small amounts of these processing aids may, or may not, become incorporated into the composition. Additionally, as illustrated in the examples below, the copolymer and terpolymers can be dissolved in organic solvents along with the PVC and then cast to form a film.
The invention is further described in the following non-limiting examples.